Data are not yet available for ATP, but using thrombin as an agonist it has been shown that the initial transient rise in [Ca2+Ii is both necessary and sufficient to account for PGI, release (Hallam et al., 1988). ATP, like thrombin, also opens receptor-operated Ca? +-selective channels in endothelial cells (Hallam & Pearson, 1986) and these may be more important for EDRF production. Similar AT...

Leukotrienes are metabolites of arachidonic acid derived from the action of 5-LO (5-lipoxygenase). The immediate product of 5-LO is LTA4 (leukotriene A4), which is enzymatically converted into either LTB4 (leukotriene B4) by LTA4 hydrolase or LTC4 (leukotriene C4) by LTC4 synthase. The regulation of leukotriene production occurs at various levels, including expression of 5-LO, translocation of ...

5,8,11-Eicosatrienoic acid was converted by mouse mastocytoma cells stimulated with ionophore A23187 to two slow reacting substances. These were characterized by spectroscopy and by chemical and enzymatic degradations as two geometrical isomers of 5-hydroxy-6-S-glutathionyl-7,9,11-eicosatrienoic acid (E,E,Z; leukotriene C3 and E,E,E; 11-trans-leukotriene C3). Corresponding cysteinylglycine comp...